In short, I would like to perform the unmarshalling as mentioned here but along with Map I will have one more @XmlElement. So one field is annotated with (Map field) @XmlPath(".") and another field with (String field) @XmlElement and then I would like to perform unmarshalling.
My main goal of the application is to convert XML->JSON and JSON->XML using the JAXB/Moxy and Jackson library. I am trying to unmarshal the XML and map it to the Java POJO. My XML can have some dedicated elements and some user-defined elements which can appear random so I would like to store them in Map<String, Object>. Hence, I am making use of XMLAdapter. I am following the blog article to do so. I am not doing exactly the same but a bit different.
The problem I am facing is during unmarshalling the dedicated fields are not taken into consideration at all. All the values are unmarshalled to Map<String.Object>. As per my understanding it's happening because of the annotation @XmlPath(".") and usage of XMLAdapter but If I remove this annotation then it won't work as expected. Can someone please help me with this issue? The marshaling works fine with both @XmlPath(".") and XMLAdapter. The problem is arising only during unmarshalling.
Following is my XML that I would like to convert to JSON: (Note: Name and Age are dedicated fields and others is the user-defined field.)
<Customer xmlns:google="https://google.com">
<name>BATMAN</name>
<age>2008</age>
<google:main>
<google:sub>bye</google:sub>
</google:main>
</Customer>
Following is my Customer class used for marshaling, unmarshalling by Moxy and Jackson: (Note: Name and Age are dedicated fields and others is the user-defined field. I want others to store only the values that cannot be mapped directly to POJO such as google:main and its children from above XML)
@XmlRootElement(name = "Customer")
@XmlType(name = "Customer", propOrder = {"name", "age", "others"})
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {
private String name;
private String age;
@XmlPath(".")
@XmlJavaTypeAdapter(TestAdapter.class)
private Map<String, Object> others;
//Getter, Setter and other constructors
}
Following is my TestAdapter class which will be used for the Userdefined fields:
class TestAdapter extends XmlAdapter<Wrapper, Map<String, Object>> {
@Override
public Map<String, Object> unmarshal(Wrapper value) throws Exception {
System.out.println("INSIDE UNMARSHALLING METHOD TEST");
final Map<String, Object> others = new HashMap<>();
for (Object obj : value.getElements()) {
final Element element = (Element) obj;
final NodeList children = element.getChildNodes();
//Check if its direct String value field or complex
if (children.getLength() == 1) {
others.put(element.getNodeName(), element.getTextContent());
} else {
List<Object> child = new ArrayList<>();
for (int i = 0; i < children.getLength(); i++) {
final Node n = children.item(i);
if (n.getNodeType() == Node.ELEMENT_NODE) {
Wrapper wrapper = new Wrapper();
List childElements = new ArrayList();
childElements.add(n);
wrapper.elements = childElements;
child.add(unmarshal(wrapper));
}
}
others.put(element.getNodeName(), child);
}
}
return others;
}
@Override
public Wrapper marshal(Map<String, Object> v) throws Exception {
Wrapper wrapper = new Wrapper();
List elements = new ArrayList();
for (Map.Entry<String, Object> property : v.entrySet()) {
if (property.getValue() instanceof Map) {
elements.add(new JAXBElement<Wrapper>(new QName(property.getKey()), Wrapper.class, marshal((Map) property.getValue())));
} else {
elements.add(new JAXBElement<String>(new QName(property.getKey()), String.class, property.getValue().toString()));
}
}
wrapper.elements = elements;
return wrapper;
}
}
@Getter
class Wrapper {
@XmlAnyElement
List elements;
}
And finally, my Main class will be used for marshaling and unmarshalling. Also, to convert to JSON and XML.
class Main {
public static void main(String[] args) throws JAXBException, XMLStreamException, JsonProcessingException {
//XML to JSON
JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
InputStream inputStream = Main.class.getClassLoader().getResourceAsStream("Customer.xml");
final XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
final XMLStreamReader streamReader = xmlInputFactory.createXMLStreamReader(inputStream);
final Customer customer = unmarshaller.unmarshal(streamReader, Customer.class).getValue();
final ObjectMapper objectMapper = new ObjectMapper();
final String jsonEvent = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(customer);
System.out.println(jsonEvent);
//JSON to XML
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.marshal(customer, System.out);
}
}
When I convert the XML->JSON then I get the following output: (If you observe the fields name and age are not taken as the dedicated fields from Customer class rather its taken as random fields and written within the others)
{
"name" : "",
"age" : "",
"others" : {
"google:main" : [ {
"google:sub" : "bye"
} ],
"name" : "BATMAN",
"age" : "2008"
}
}
I want my output to be something like this: (I want my dedicated fields to be mapped first then if there are any unknown fields then map them later within others MAP). Please note that I do not want to get others tag within my JSON. I want to get the names of the fields only for the dedicated fields.
{
"name": "BATMAN",
"age": 2008,
"google:main": {
"google:sub": "bye"
}
}
Following is the XML that I would like to get during the marshaling. Also, please note I am using @XmlPath(".") so that I do not get the others node within my XML during marshaling.
<Customer>
<name>BATMAN</name>
<age>2008</age>
<google:main>>
<google:sub>bye</google:sub>
</google:main>
</Customer>
The marshaling is working fine. The problem is happening during .unmarshaling As per my understanding it's happening because of the annotation @XmlPath(".") with XMLAdapter but If I remove this annotation then it won't work as expected. Can someone please help me with this issue?
** Edited **
I thought of a few workarounds but nothing seems to work for me. They are getting messed up due to @XmlPath("."). Still looking for some idea or workarounds. Any help would be really appreciated.
ah, finally some relief. This issue ate my head a lot but I was finally able to find a workaround. Tried a lot of things and reached out to many people but nothing seems to work and I thought it's an issue from the JAXB/Moxy library. I was able to find a workaround. Hope it helps someone in the future and do not get frustrated like me :)
I used 2 fields one with @XmlAnyElement(lax=true) List<Object> for storing the elements during the marshaling and another Map<String, Object> with custom serialization for JSON. In addition to this, I got to know that we can use beforeMarshal, afterMarshal, beforeUnmarshal, afterMarshal methods. The name itself suggests what it does.
In my case, I used the beforeMarshal method to add the unknown data from my Map<String, Object> to List<Object> so during the marshaling values from List<Object> will be used. I removed the XMLAdapter.
Also, the afterUnmarshal method to add the read unknown elements from List<Object> to Map<String, Object> so Jackson can utilize it and write to JSON using CustomSearlizer.
Basically, it's a kind of hide-and-show approach. List<Object> will be used during the unmarshalling and marshaling by JAXB/Moxy. Map<String, Object> will be used during the serialization and deserialization by Jackson.
Custome.class with my beforeMarshal and afterUnmarshalling: (It seems bit complex basically it exchanges the data as mentioned above. I will have complex data so I need to recursively loop and arrange. You can make changes according to your need)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, visible = true, property = "isA")
@JsonInclude(Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@XmlRootElement(name = "Customer")
@XmlType(name = "Customer", propOrder = {"name", "age", "otherElements"})
@XmlAccessorType(XmlAccessType.FIELD)
@Getter
@Setter
@AllArgsConstructor
@ToString
public class Customer {
@XmlTransient
private String isA;
private String name;
private String age;
@XmlAnyElement(lax = true)
@JsonIgnore
private List<Object> otherElements = new ArrayList<>();
@JsonIgnore
@XmlTransient
private Map<String, Object> userExtensions = new HashMap<>();
@JsonAnyGetter
@JsonSerialize(using = CustomExtensionsSerializer.class)
public Map<String, Object> getUserExtensions() {
return userExtensions;
}
@JsonAnySetter
public void setUserExtensions(String key, Object value) {
userExtensions.put(key, value);
}
private void beforeMarshal(Marshaller m) throws ParserConfigurationException {
System.out.println("Before Marshalling User Extension: " + userExtensions);
ExtensionsModifier extensionsModifier = new ExtensionsModifier();
otherElements = extensionsModifier.Marshalling(userExtensions);
System.out.println("Before Marshalling Final Other Elements " + otherElements);
userExtensions = new HashMap<>();
}
private void afterUnmarshal(Unmarshaller m, Object parent) throws ParserConfigurationException {
System.out.println("After Unmarshalling : " + otherElements);
ExtensionsModifier extensionsModifier = new ExtensionsModifier();
userExtensions = extensionsModifier.Unmarshalling(otherElements);
otherElements = new ArrayList();
}
}
Then the ExtensionsModifier.class which will be called by beforeMarshal and afterUnmarshalling method:
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ExtensionsModifier {
private javax.xml.parsers.DocumentBuilderFactory documentFactory;
private javax.xml.parsers.DocumentBuilder documentBuilder;
private org.w3c.dom.Document document;
public ExtensionsModifier() throws ParserConfigurationException {
documentFactory = DocumentBuilderFactory.newInstance();
documentBuilder = documentFactory.newDocumentBuilder();
document = documentBuilder.newDocument();
}
public List<Object> Marshalling(Map<String, Object> userExtensions) throws ParserConfigurationException {
if (userExtensions == null) {
return null;
}
List<Object> tempElement = new ArrayList<>();
for (Map.Entry<String, Object> property : userExtensions.entrySet()) {
Element root = document.createElement(property.getKey());
if (property.getValue() instanceof Map) {
List<Object> mapElements = Marshalling((Map<String, Object>) property.getValue());
mapElements.forEach(innerChildren -> {
if (innerChildren instanceof Element) {
if (((Element) innerChildren).getTextContent() != null) {
root.appendChild(document.appendChild((Element) innerChildren));
}
}
});
tempElement.add(root);
} else if (property.getValue() instanceof String) {
root.setTextContent(((String) property.getValue()));
tempElement.add(root);
} else if (property.getValue() instanceof ArrayList) {
for (Object dupItems : (ArrayList<Object>) property.getValue()) {
if (dupItems instanceof Map) {
Element arrayMap = document.createElement(property.getKey());
List<Object> arrayMapElements = Marshalling((Map<String, Object>) dupItems);
arrayMapElements.forEach(mapChildren -> {
if (mapChildren instanceof Element) {
if (((Element) mapChildren).getTextContent() != null) {
arrayMap.appendChild(document.appendChild((Element) mapChildren));
}
}
});
tempElement.add(arrayMap);
} else if (dupItems instanceof String) {
Element arrayString = document.createElement(property.getKey());
arrayString.setTextContent((String) dupItems);
tempElement.add(arrayString);
}
}
}
}
return tempElement;
}
public Map<String, Object> Unmarshalling(List<Object> value) {
if (value == null) {
return null;
}
final Map<String, Object> extensions = new HashMap<>();
for (Object obj : value) {
org.w3c.dom.Element element = (org.w3c.dom.Element) obj;
final NodeList children = element.getChildNodes();
//System.out.println("Node Name : " + element.getNodeName() + " Value : " + element.getTextContent());
List<Object> values = (List<Object>) extensions.get(element.getNodeName());
if (values == null) {
values = new ArrayList<Object>();
}
if (children.getLength() == 1) {
values.add(element.getTextContent());
extensions.put(element.getNodeName(), values);
} else {
List<Object> child = new ArrayList<>();
for (int i = 0; i < children.getLength(); i++) {
final Node n = children.item(i);
if (n.getNodeType() == Node.ELEMENT_NODE) {
List<Object> childElements = new ArrayList();
childElements.add(n);
values.add(Unmarshalling(childElements));
child.add(Unmarshalling(childElements));
}
}
extensions.put(element.getNodeName(), values);
}
}
return extensions;
}
}
Following is my CustomSearlizer which will be used by Jackson to create JSON:
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Map;
public class CustomExtensionsSerializer extends JsonSerializer<Map<String, Object>> {
private static final ObjectMapper mapper = new ObjectMapper();
@Override
public void serialize(Map<String, Object> value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
System.out.println("Custom Json Searlizer: " + value);
recusiveSerializer(value, gen, serializers);
}
public void recusiveSerializer(Map<String, Object> value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
for (Map.Entry<String, Object> extension : value.entrySet()) {
if (extension.getValue() instanceof Map) {
//If instance is MAP then call the recursive method
recusiveSerializer((Map) extension.getValue(), gen, serializers);
} else if (extension.getValue() instanceof String) {
//If instance is String directly add it to the JSON
gen.writeStringField(extension.getKey(), (String) extension.getValue());
} else if (extension.getValue() instanceof ArrayList) {
//If instance if ArrayList then loop over it and add it to the JSON after calling recursive method
//If size more than 1 add outer elements
if (((ArrayList<Object>) extension.getValue()).size() > 1) {
gen.writeFieldName(extension.getKey());
gen.writeStartObject();
for (Object dupItems : (ArrayList<Object>) extension.getValue()) {
if (dupItems instanceof Map) {
recusiveSerializer((Map) dupItems, gen, serializers);
} else {
gen.writeStringField(extension.getKey(), (String) dupItems);
}
}
gen.writeEndObject();
} else {
for (Object dupItems : (ArrayList<Object>) extension.getValue()) {
if (dupItems instanceof Map) {
gen.writeFieldName(extension.getKey());
gen.writeStartObject();
recusiveSerializer((Map) dupItems, gen, serializers);
gen.writeEndObject();
} else {
gen.writeStringField(extension.getKey(), (String) dupItems);
}
}
}
}
}
}
}
If I provide input as following XML:
<Customer xmlns:google="https://google.com">
<name>Rise Against</name>
<age>2000</age>
<google:main>
<google:sub>MyValue</google:sub>
<google:sub>MyValue</google:sub>
</google:main>
</Customer>
Then I get the following JSON as output:
{
"isA" : "Customer",
"name" : "Rise Against",
"age" : "2000",
"google:main" : {
"google:sub" : "MyValue",
"google:sub" : "MyValue"
}
}
Viceversa would also work fine. Hope it's clear if not leave a comment will try to respond.